Obsessive-Compulsive Disorder (OCD) is a chronic and debilitating anxiety disorder. People with OCD often experience recurrent unwanted thoughts, called obsessions, and repetitive behaviors, called compulsions. These thoughts and behaviors interfere with everyday life to a great extent. Currently, the most frequently used psychosocial treatment for OCD is cognitive-behavioral therapy (CBT) that incorporates exposure with ritual prevention (EX/RP). However, although effective, this treatment approach is largely inaccessible, time-consuming, labor-intensive, and expensive. A stepped-care approach to treating OCD may be more cost-effective and therefore more accessible for many individuals. Stepped-care CBT begins with the least expensive, least intrusive, most accessible option, and works up to the most expensive option if the less intrusive treatments do not work. This study will determine the benefits and cost-effectiveness of a stepped care treatment program for OCD.